Method for depositing a metal chalcogenide on a substrate by cyclical deposition

ABSTRACT

A method for depositing a metal chalcogenide on a substrate by cyclical deposition is disclosed. The method may include, contacting the substrate with at least one metal containing vapor phase reactant and contacting the substrate with at least one chalcogen containing vapor phase reactant. Semiconductor device structures including a metal chalcogenide deposited by the methods of the disclosure are also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/729,485 filed Oct. 10, 2017 and entitled “METHOD FOR DEPOSITING AMETAL CHALCOGENIDE ON A SUBSTRATE BY CYCLICAL DEPOSITION,” thedisclosure of which is hereby incorporated by reference in its entiretyfor all purposes.

PARTIES OF JOINT RESEARCH AGREEMENT

The invention claimed herein was made by, or on behalf of, and/or inconnection with a joint research agreement between the University ofHelsinki and ASM Microchemistry Oy. The agreement was in effect on andbefore the date the claimed invention was made, and the claimedinvention was made as a result of activities undertaken within the scopeof the agreement.

FIELD OF INVENTION

The present disclosure relates generally to methods for depositing ametal chalcogenide on a substrate by cyclical deposition andparticularly to the cyclical deposition of tin disulfide or germaniumdisulfide. The disclosure also relates to semiconductor devicestructures including a metal chalcogenide thin film formed by cyclicaldeposition.

BACKGROUND OF THE DISCLOSURE

The interest in two-dimensional (2D) materials has increaseddramatically in recent years due to their potential in improvingperformance in next generation electronic devices. For example, graphenehas been the most studied 2D material to date and exhibits highmobility, transmittance, mechanical strength and flexibility. However,the lack of a band gap in pure graphene has limited its performance insemiconductor device structures, such as transistors. Such limitationsin graphene have stimulated research in alternative 2D materials asanalogues of graphene. Recently, transition metal chalcogenides, andparticularly transition metal dichalcogenides, have attractedconsiderable research attention as an alternative to graphene.Transition metal dichalcogenides may have stoichiometry of MX₂, whichdescribes a transition metal sandwiched between two layers of chalcogenatoms, with strong in-plane covalent bonding between the metal-chalcogenand weak out-of-plane van der Walls bonding between the layers.

However, there are few scalable, low temperature methods to produce 2Dmaterials. Currently, mechanical exfoliation of bulk crystals is themost commonly used method of formation, but although this methodproduces good quality crystals, the method is unable to producecontinuous films and is very labor intensive, making such a method notviable for industrial production. Chemical vapor deposition (CVD) hasbeen used to deposit 2D materials, but current CVD processes for metalchalcogenides, such as, for example, tin disulfide (SnS₂), operate attemperatures above 600° C. and are unable to produce continuous, largearea 2D materials. Accordingly, methods are desirable that are capableof producing 2D materials with a suitable band gap, at a reduceddeposition temperature and with atomic level film thickness control.

SUMMARY OF THE DISCLOSURE

This summary is provided to introduce a selection of concepts in asimplified form. These concepts are described in further detail in thedetailed description of example embodiments of the disclosure below.This summary is not intended to identify key features or essentialfeatures of the claimed subject matter, nor is it intended to be used tolimit the scope of the claimed subject matter.

In some embodiments, methods for depositing a metal chalcogenide on asubstrate by cyclical deposition are provided. The method may comprise;contacting the substrate with at least one metal containing vapor phasereactant comprising, a partial chemical structure represented by thechemical formula M-O—C wherein a metal atom is bonded to an oxygen atom(O), and said oxygen (O) atom is bonded to a carbon (C) atom; andcontacting the substrate with at least one chalcogen containing vaporphase reactant. The embodiments of the disclosure also providesemiconductor device structures comprising a metal chalcogenidedeposited by the methods described herein.

For the purpose of summarizing the invention and the advantages achievedover the prior art, certain objects and advantages of the invention havebeen described herein above. Of course, it is to be understood that notnecessarily all such objects or advantages may be achieved in accordancewith any particular embodiment of the invention. Thus, for example,those skilled in the art will recognize that the invention may beembodied or carried out in a manner that achieves or optimizes oneadvantage or group of advantages as taught or suggested herein withoutnecessarily achieving other objects or advantages as may be taught orsuggested herein.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments will becomereadily apparent to those skilled in the art from the following detaileddescription of certain embodiments having reference to the attachedfigures, the invention not being limited to any particular embodiment(s)disclosed.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

While the specification concludes with claims particularly pointing outand distinctly claiming what are regarded as embodiments of theinvention, the advantages of embodiments of the disclosure may be morereadily ascertained from the description of certain examples of theembodiments of the disclosure when read in conjunction with theaccompanying drawings, in which:

FIG. 1 is a process flow diagram illustrating an exemplary cyclicaldeposition method according to the embodiments of the disclosure;

FIG. 2 illustrates grazing incidence x-ray diffraction (GIXRD) data fortin dichalcogenide thin films deposited according to the embodiments ofthe disclosure;

FIG. 3 illustrates further grazing incidence x-ray diffraction (GIXRD)data for tin dichalcogenide thin films deposited according to theembodiments of the disclosure;

FIG. 4 is a high-angle annular dark-field scanning transmission electronmicroscopy (HAADF-STEM) image of a structure comprising a tindichalcogenide 2D material deposited according to the embodiments of thedisclosure;

FIG. 5 illustrates a Raman spectrum obtained from a tin dichalcogenidethin film deposited according to the embodiments of the disclosure;

FIG. 6 illustrates an exemplary semiconductor device structure includinga metal chalcogenide thin film deposited according to the embodiments ofthe disclosure;

FIG. 7 illustrates an exemplary reaction system which may be used todeposit metal chalcogenide thin films according to the embodiments ofthe disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Although certain embodiments and examples are disclosed below, it willbe understood by those in the art that the invention extends beyond thespecifically disclosed embodiments and/or uses of the invention andobvious modifications and equivalents thereof. Thus, it is intended thatthe scope of the invention disclosed should not be limited by theparticular disclosed embodiments described below.

The illustrations presented herein are not meant to be actual views ofany particular material, structure, or device, but are merely idealizedrepresentations that are used to describe embodiments of the disclosure.

As used herein, the term “substrate” may refer to any underlyingmaterial or materials that may be used, or upon which, a device, acircuit or a film may be formed.

As used herein, the term “cyclic deposition” may refer to the sequentialintroduction of precursors (reactants) into a reaction chamber todeposit a film over a substrate and includes deposition techniques suchas atomic layer deposition and cyclical chemical vapor deposition.

As used herein, the term “atomic layer deposition” (ALD) may refer to avapor deposition process in which deposition cycles, preferably aplurality of consecutive deposition cycles, are conducted in a processchamber. Typically, during each cycle the precursor is chemisorbed to adeposition surface (e.g., a substrate surface or a previously depositedunderlying surface such as material from a previous ALD cycle), forminga monolayer or sub-monolayer that does not readily react with additionalprecursor (i.e., a self-limiting reaction). Thereafter, if necessary, areactant (e.g., another precursor or reaction gas) may subsequently beintroduced into the process chamber for use in converting thechemisorbed precursor to the desired material on the deposition surface.Typically, this reactant is capable of further reaction with theprecursor. Further, purging steps may also be utilized during each cycleto remove excess precursor from the process chamber and/or remove excessreactant and/or reaction byproducts from the process chamber afterconversion of the chemisorbed precursor. Further, the term “atomic layerdeposition,” as used herein, is also meant to include processesdesignated by related terms such as, “chemical vapor atomic layerdeposition,” “atomic layer epitaxy” (ALE), molecular beam epitaxy (MBE),gas source MBE, or organometallic MBE, and chemical beam epitaxy whenperformed with alternating pulses of precursor composition(s), reactivegas, and purge (e.g., inert carrier) gas.

As used herein, the term “cyclical chemical vapor deposition” may referto any process wherein a substrate is sequentially exposed to two ormore volatile precursors, which react and/or decompose on a substrate toproduce a desired deposition.

As used herein, the term “chalcogen containing vapor phase reactant” mayrefer to a reactant (precursor) containing a chalcogen, wherein achalcogen is an element from Group VI of the periodic including sulphur,selenium, and tellurium.

As used herein, the term “film” and “thin film” may refer to anycontinuous or non-continuous structures and material deposited by themethods disclosed herein. For example, “film” and “thin film” couldinclude 2D materials, nanorods, nanotubes, or nanoparticles or evenpartial or full molecular layers or partial or full atomic layers orclusters of atoms and/or molecules. “Film” and “thin film” may comprisematerial or a layer with pinholes, but still be at least partiallycontinuous.

As used herein, the term “partial chemical structure” may refer to thechemical structure of a portion of a chemical compound, i.e., thechemical structure of less than the whole chemical compound.

As used herein, the term “2D material” or “two-dimensional material” mayrefer to a nanometer scale crystalline material one, two or three atomsin thickness. In addition “2D materials” or “two-dimensional material”may also refer to an ordered nanometer scale crystalline structurecomposed of multiple monolayers of crystalline materials ofapproximately three atoms in thickness per monolayer.

The embodiments of the disclosure may include methods for depositing ametal chalcogenide on a substrate by cyclical deposition andparticularly methods for depositing a tin disulfide (SnS₂) thin film ora germanium disulfide (GeS₂) thin film by atomic layer depositionprocesses. As a non-limiting example, Tin disulfide is an emergingmaterial, which has a 2D crystal structure, similar to the well-knowntransition metal dichalcogenides (TMDCs), such as, for example,molybdenum disulfide (MoS₂). In comparison to the most studied 2Dmaterial, graphene, tin disulfide has a sizable band gap (bulk ˜1.8-2.2eV, monolayer 2.8 eV), which makes tin disulfide more suitable insemiconductor device structures, such as, for example, field effecttransistors (FETs). Initial research involving tin disulfide as thechannel material in a FET device have shown electrical propertiescomparable to molybdenum disulfide, such as, for example, a mobility upto 50-200 cm²V⁻¹s⁻¹ and on/off ratios of 10⁶ to 10⁸, as well as a strongphotoresponsivity of 100 AW⁻¹. Other possible application areas for tindisulfide thin films include, but are not limited to, catalysis, energystorage, and photovoltaics.

Current methods for forming a tin disulfide thin film are not suitablefor forming high quality, conformal, low temperature thin films. Tindisulfide crystals may be formed by mechanical exfoliation of a bulk tindisulfide crystal, but such methods are not suitable for forming tindisulfide to a thickness accuracy on the atomic scale on suitablesubstrates. In addition, chemical vapor deposition of tin disulfide hasbeen demonstrated but such processes operate at high depositiontemperatures (greater than 600° C.) and are unsuitable to producenanoscale, conformal, thin films.

Cyclical deposition methods, such as cyclical chemical vapor depositionand atomic layer deposition techniques, are inherently scalable andoffer atomically accurate film thickness control, which is crucial inthe deposition of high quality 2D materials. In addition, cyclicdeposition methods, such as atomic layer deposition, arecharacteristically conformal, thereby providing the ability to uniformlycoat three dimensional structures. Atomic layer deposition of tindisulfide has been demonstrated utilizing Sn(NMe₂)₄ and H₂S as the tinand chalcogenide precursors respectively, Ham et al., ACS AppliedMaterial Interfaces, 5, (2013) 8880. However, such prior art atomiclayer deposition processes for forming tin disulfide may be problematic.For example, the tin disulfide may need to be deposited over a narrowtemperature range and require post-deposition annealing processes tocrystallize the tin disulfide. In addition, the Sn(NMe₂)₄ precursor maybe somewhat unstable, which may result in poor quality films over largearea substrates, such as, for example, 200 mm or 300 mm substrates.

Accordingly, methods are desired which are capable of depositing metaldichalcogenide films at low temperature, conformally and with atomicthickness accuracy. In addition, semiconductor device structurescomprising a metal dichalcogenide film are desirable.

A non-limiting example embodiment of a cyclical deposition process mayinclude ALD, wherein ALD is based on typically self-limiting reactions,whereby sequential and alternating pulses of reactants are used todeposit about one atomic (or molecular) monolayer of material perdeposition cycle. The deposition conditions and precursors are typicallyselected to provide self-saturating reactions, such that an absorbedlayer of one reactant leaves a surface termination that is non-reactivewith the vapor phase reactants of the same reactant. The substrate issubsequently contacted with a different reactant that reacts with theprevious termination to enable continued deposition. Thus, each cycle ofalternating pulsed reactants typically leaves no more than about onemonolayer of the desired material. However, as mentioned above, theskilled artisan will recognize that in one or more ALD cycles more thanone monolayer of material may be deposited, for example, if some gasphase reactions occur despite the alternating nature of the process.

In an ALD-type process for depositing a metal chalcogenide films, onedeposition cycle may comprise exposing the substrate to a firstreactant, removing any unreacted first reactant and reaction byproductsfrom the reaction space and exposing the substrate to a second reactant,followed by a second removal step. The first reactant may comprise ametal containing precursor, such as a tin or a germanium containingprecursor, and the second reactant may comprise a chalcogen containingprecursor.

Precursors may be separated by inert gases, such as argon (Ar) ornitrogen (N₂), to prevent gas phase reactions between reactants andenable self-saturating surface reactions. In some embodiments, however,the substrate may be moved to separately contact a first vapor phasereactant and a second vapor phase reactant. Because the reactionsself-saturate, strict temperature control of the substrates and precisedosage control of the precursor may not be required. However, thesubstrate temperature is preferably such that an incident gas speciesdoes not condense into monolayers nor decompose on the substratesurface. Surplus chemicals and reaction byproducts, if any, are removedfrom the substrate surface, such as by purging the reaction space or bymoving the substrate, before the substrate is contacted with the nextreactive chemical. Undesired gaseous molecules can be effectivelyexpelled from the reaction space with the help of an inert purging gas.A vacuum pump may be used to assist in the purging process.

Reactors capable of being used to deposit or grow thin films can be usedfor the deposition. Such reactors include ALD reactors, as well as CVDreactors equipped with appropriate equipment and means for providing theprecursors. According to some embodiments, a showerhead reactor may beused.

Examples of suitable reactors that may be used include commerciallyavailable single substrate (or single wafer) deposition equipment suchas Pulsar® reactors (such as the Pulsar® 2000 and the Pulsar® 3000 andPulsar® XP ALD), and EmerALD® XP and the EmerALD® reactors, availablefrom ASM America, Inc. of Phoenix, Ariz. and ASM Europe B.V., Almere,Netherlands. Other commercially available reactors include those fromASM Japan K.K (Tokyo, Japan) under the tradename Eagle® XP and XP8. Insome embodiments the reactor is a spatial ALD reactor, in which thesubstrates moves or rotates during processing.

In some embodiments a batch reactor may be used. Suitable batch reactorsinclude, but are not limited to, Advance® 400 Series reactorscommercially available from and ASM Europe B.V. (Almere, Netherlands)under the trade names A400 and A412 PLUS. In some embodiments, avertical batch reactor is utilized in which the boat rotates duringprocessing, such as the A412. Thus, in some embodiments, the wafersrotate during processing. In other embodiments, the batch reactorcomprises a mini-batch reactor configured to accommodate 10 or fewerwafers, 8 or fewer wafers, 6 or fewer wafers, 4 or fewer wafers, or 2wafers. In some embodiments in which a batch reactor is used,wafer-to-wafer non-uniformity is less than 3% (1 sigma), less than 2%,less than 1% or even less than 0.5%.

The deposition processes described herein can optionally be carried outin a reactor or reaction space connected to a cluster tool. In a clustertool, because each reaction space is dedicated to one type of process,the temperature of the reaction space in each module can be keptconstant, which improves the throughput compared to a reactor in whichthe substrate is heated up to the process temperature before each run.Additionally, in a cluster tool it is possible to reduce the time topump the reaction space to the desired process pressure levels betweensubstrates.

A stand-alone reactor can be equipped with a load-lock. In that case, itis not necessary to cool down the reaction space between each run. Insome embodiments, a deposition process for depositing a thin filmcomprising a metal dichalcogenide thin film may comprise a plurality ofdeposition cycles, for example ALD cycles.

In some embodiments, cyclical deposition processes are used to formmetal chalcogenide thin films on a substrate and the cyclical depositionprocess may be an ALD type process. In some embodiments, the cyclicaldeposition may be a hybrid ALD/CVD or cyclical CVD process. For example,in some embodiments the deposition or growth rate of the ALD process maybe low compared with a CVD process. One approach to increase the growthrate may be that of operating at a higher substrate temperature thanthat typically employed in an ALD process, resulting in a chemical vapordeposition process, but still taking advantage of the sequentialintroduction or precursor, such a process may be referred to as cyclicalCVD.

According to some embodiments of the disclosure, ALD processes are usedto form metal chalcogenide thin films on a substrate, such as anintegrated circuit workpiece. In some embodiments, each ALD cycle maycomprise two distinct deposition steps or phases. In a first phase ofthe deposition cycle (“the metal phase”), the substrate surface on whichdeposition is desired is contacted with a first vapor phase reactantcomprising at least one tin (Sn) containing vapor phase reactant or atleast one germanium (Ge) containing vapor phase reactant whichchemisorbs onto the substrate surface, forming no more than about onemonolayer of reactant species on the surface of the substrate. In asecond phase of the deposition cycle (“the chalcogen phase”), thesubstrate surface on which deposition is desired is contacted with asecond vapor phase reactant comprising at least one chalcogen containingvapor phase reactant which reacts with the previously chemisorbedspecies to form a tin dichalcogenide thin film.

In some embodiments, the at least one metal containing vapor phasereactant, also referred to here as the “metal compound” may comprise apartial chemical structure represented by the formula:

M-O—C

wherein a metal (M) is bonded to an oxygen (O) atom, and said oxygen (O)atom is bonded to a carbon (C) atom. In some embodiments, the bondsbetween the atoms may comprise one or more single bonds whereas in otherembodiments the bonds between the atoms may comprise one or more doublebonds. In some embodiments of the disclosure, the metal containing vaporphase reactant comprises at least one of a tin (Sn) containing vaporphase reactant, or a germanium (Ge) containing vapor phase reactant,

In some embodiments, the tin (Sn) containing vapor phase reactant or tin(Sn) precursor, also referred to here as the “tin compound” may compriseat least one tin (Sn) containing vapor phase reactant with a partialchemical structure represented by the formula;

Sn—O—C

wherein a tin (Sn) atom is bonded to an oxygen (O) atom, and said oxygen(O) atom is bonded to a carbon (C) atom, wherein the bonds between thedisclosed atoms may comprise single or double bonds. In some embodimentsof the disclosure, the at least one tin (Sn) containing vapor phasereactant is represented by the chemical formula Sn(OR)_(x), wherein R isa C₁-C₅ alkyl group, or R is an OCCH₃ group, and x in an integer from2-6. As a non-limiting example, in some embodiments, the tin (Sn)containing vapor phase reactant may comprise tin (IV) acetate(Sn(OAc)₄). As a further non-limiting example, in some embodiments, thetin (Sn) containing vapor phase reactant may comprise tin (IV)tert-butoxide (Sn(O^(t)Bu)₄).

In some embodiments, the tin (Sn) precursor, also referred to here asthe “tin compound” may comprise at least one tin (Sn) containing vaporphase reactant with a partial chemical structure represented by theformula;

wherein a tin (Sn) atom is bonded or coordinated to two oxygen (O)atoms, and said oxygen (O) atom is bonded to a carbon atom (C) throughone single bond and one double bond and R can be hydrocarbon group,substituted or unsubstituted, such as C₁-C₃ alkyl, for example —CH₃.

In some embodiments, the tin (Sn) precursor, also referred to here asthe “tin compound” may comprise a monodentate ligand. In someembodiments, the tin (Sn) precursor, also referred to here as the “tincompound” may comprise a bidentate ligand. In some embodiments, the tin(Sn) precursor, also referred to here as the “tin compound” may comprisea multidentate ligand. In some embodiments, the tin (Sn) precursor maynot comprise a monodentate ligand. In some embodiments, the tin (Sn)precursor does not consist of a monodentate ligand. In some embodiments,the tin (Sn) precursor may not comprise a betadiketonate ligand, such asacetylacetonate (acac) or 2,2,6,6-tetramethyl-3,5-heptanedionate (thd)ligand. In some embodiments, the tin (Sn) precursor may not comprisemore than two betadiketonate ligands, such as acetylacetonate (acac) or2,2,6,6-tetramethyl-3,5-heptanedionate (thd) ligand. In someembodiments, the tin (Sn) precursor may not comprise an adduct ligand,whereas in other embodiments the tin (Sn) precursor may comprise one ormore adduct ligands. In some embodiments, Sn in the tin (Sn) precursorhas oxidation state of +IV. In some embodiments, Sn in the tin (Sn)precursor has oxidation state of +II. In some embodiments, Sn in the tin(Sn) precursor has not oxidation state of +II.

In some embodiments, the tin (Sn) precursor, also referred to here asthe “tin compound” may comprise at least one tin (Sn) containing vaporphase reactant with a partial chemical structure represented by theformula;

wherein a tin (Sn) atom is bonded or coordinated to two oxygen (O)atoms, and said oxygen (O) atom is bonded to a carbon atom (C) throughone single bond and one double bond and R can be a hydrocarbon group,substituted or unsubstituted, such as C₁-C₃ alkyl, for example —CH₃ andwherein L is a hydrocarbon group, such as alkyl group, in which thehydrocarbon may or may not contain heteroatoms (i.e., other than C orH).

In some embodiments, the tin (Sn) precursor, also referred to here asthe “tin compound” may comprise at least one tin (Sn) containing vaporphase reactant with a partial chemical structure represented by theformula;

L-Sn—O—C

wherein a tin (Sn) atom is bonded or coordinated to an oxygen (O) atom,and said oxygen (O) atom is bonded to a carbon atom (C) and wherein L isa hydrocarbon group, such as alkyl group, in which the hydrocarbon mayor may not contain heteroatoms (i.e., other than C or H). In someembodiments, the tin (Sn) precursor, also referred to here as the “tincompound” may comprise at least one tin (Sn) containing vapor phasereactant with a partial chemical structure represented by the formula;

X—Sn-L

wherein X is halide, such as Cl, or other than hydrocarbon containingligand and L is a hydrocarbon group, such as alkyl group, in which thehydrocarbon may or may not contain heteroatoms (i.e., other than C orH).

In some embodiments, the tin (Sn) precursor, also referred to here asthe “tin compound” may comprise at least one tin (Sn) containing vaporphase reactant with a partial chemical structure represented by theformula;

X_(y)—Sn-L_(w-y)

wherein X is halide, such as Cl, or other than hydrocarbon containingligand, y is from 0 to w or 1 to w−1, w is from 2 to 4 and L is ahydrocarbon group, such as alkyl group, in which the hydrocarbon may ormay not contain heteroatoms (i.e., other than C or H).

In some embodiments, the tin (Sn) precursor, also referred to here asthe “tin compound” may comprise at least one tin (Sn) containing vaporphase reactant with a partial chemical structure represented by theformula;

X_(y)—Sn-L_(4-y)

wherein X is halide, such as Cl, or other than hydrocarbon containingligand, y is from 0 to 4 or 1 to 3 and L is a hydrocarbon group, such asalkyl group, in which the hydrocarbon may or may not contain heteroatoms(i.e., other than C or H).

In some embodiments, the metal precursor, also referred to here as themetal compound may comprise at least one of a Sn or Ge containing vaporphase reactant with a partial chemical structure represented by theformula;

-M-O—C—

wherein a metal atom M (Sn or Ge) is bonded to an oxygen (O) atom, andsaid oxygen (O) atom is bonded to a carbon (C) atom. For simplicityreasons in this document Ge precursor or Ge is called as “metalcompound” or “metal” although it can be also considered to be asemimetal precursor or semimetal, respectively. In some embodiments ofthe disclosure, the at least one metal containing vapor phase reactantis represented by the chemical formula M(OR)_(x), wherein R is a C₁-C₅alkyl group and x in an integer from 2-6 and M is Ge or Sn. As anon-limiting example, in some embodiments, the metal containing vaporphase reactant may comprise metal (IV) acetate (M(OAc)₄). As a furthernon-limiting example, in some embodiments, the metal containing vaporphase reactant may comprise metal (IV) tert-butoxide (M(O^(t)Bu)⁴).

In some embodiments, the metal precursor, also referred to here as themetal compound may comprise at least one metal (Sn or Ge) containingvapor phase reactant with a partial chemical structure represented bythe formula;

wherein a metal atom M (Sn, Ge) is bonded or coordinated to two oxygen(O) atoms, and said oxygen (O) atom is bonded to a carbon atom (C)through one single bond and one double bond and R can be hydrocarbongroup, substituted or unsubstituted, such as C₁-C₃ alkyl, for example—CH₃.

In some embodiments, the metal precursor, also referred to here as themetal compound may comprise a monodentate ligand. In some embodiments,the metal precursor, also referred to here as the metal compound maycomprise a bidentate ligand. In some embodiments, the metal precursor,also referred to here as the metal compound, may comprise a multidentateligand. In some embodiments, the metal precursor, also referred to hereas the metal compound may not comprise a monodentate ligand. In someembodiments, the metal precursor, also referred to here as the metalcompound does not consist a monodentate ligand. In some embodiments, themetal precursor, also referred to here as the metal compound, may notcomprise a betadiketonate ligand, such as acetylacetonate (acac) or2,2,6,6-tetramethyl-3,5-heptanedionate (thd) ligand. In someembodiments, the metal precursor, also referred to here as the metalcompound may not comprise more than two betadiketonate ligands, such asacetylacetonate (acac) or 2,2,6,6-tetramethyl-3,5-heptanedionate (thd)ligand. In some embodiments, the metal precursor, also referred to hereas the metal compound, may not comprise an adduct ligand, whereas inother embodiments the metal precursor, also referred to here as themetal compound, may comprise one or more adduct ligands. In someembodiments, Sn or Ge in the metal precursor has oxidation state of +IV.In some embodiments, Sn or Ge in the metal precursor has oxidation stateof +II. In some embodiments, Sn or Ge in the metal precursor has notoxidation state of +II.

In some embodiments, exposing the substrate to the at least one metalcontaining vapor phase reactant may comprise pulsing the metal precursorover the substrate for a time period between about 0.01 second and about60 seconds, between about 0.05 seconds and about 10 seconds, or betweenabout 0.1 seconds and about 5.0 seconds. In addition, during the pulsingof the metal precursor over the substrate the flow rate of the metalprecursor may be less than 2000 sccm, or less than 500 sccm, or evenless than 100 sccm. In addition, during the pulsing of the metalprecursor over the substrate the flow rate of the metal precursor mayfrom about 1 to about 2000 sccm, from about 5 to about 1000 sccm, orfrom about 10 to about 500 sccm.

Excess metal precursor, such as, for example, tin (Sn) precursor andreaction byproducts (if any) may be removed from the substrate surface,e.g., by pumping with an inert gas. For example, in some embodiments ofthe disclosure the methods may include a purge cycle wherein thesubstrate surface is purged for a time period of less than approximately2.0 seconds. Excess metal precursor and any reaction byproducts may beremoved with the aid of a vacuum generated by a pumping system.

In a second phase of the deposition cycle (“the chalcogen phase”) thesubstrate is contacted with a second vapor phase reactant comprising atleast one chalcogen containing vapor phase reactant. In some embodimentsof the disclosure, the at least one chalcogenide containing vaporreactant may comprise hydrogen sulfide (H₂S), hydrogen selenide (H₂Se),dimethyl sulfide ((CH₃)₂S), or dimethyl telluride (CH₃)₂Te.

It will be understood by one skilled in the art that any number ofchalcogen precursors may be used in the cyclical deposition processesdisclosed herein. In some embodiments, a chalcogen precursor is selectedfrom the following list: H₂S, H₂Se, H₂Te, (CH₃)₂S, (NH₄)₂S,dimethylsulfoxide ((CH₃)₂SO), (CH₃)₂Se, (CH₃)₂Te, elemental or atomic S,Se, Te, other precursors containing chalcogen-hydrogen bonds, such asH₂S₂, H₂Se₂, H₂Te₂, or chalcogenols with the formula R—Y—H, wherein Rcan be a substituted or unsubstituted hydrocarbon, preferably a C₁-C₈alkyl or substituted alkyl, such as an alkylsilyl group, more preferablya linear or branched C₁-C₅ alkyl group, and Y can be S, Se, or Te. Insome embodiments a chalcogen precursor is a thiol with the formulaR—S—H, wherein R can be substituted or unsubstituted hydrocarbon,preferably C₁-C₈ alkyl group, more linear or branched preferably C₁-C₅alkyl group. In some embodiments a chalcogen precursor has the formula(R₃Si)₂Y, wherein R₃Si is an alkylsilyl group and Y can be Se or Te. Insome embodiments, a chalcogen precursor comprises S or Se. In someembodiments, a chalcogen precursor comprises S. In some embodiments thechalcogen precursor may comprise an elemental chalcogen, such aselemental sulfur. In some embodiments, a chalcogen precursor does notcomprise Te. In some embodiments, a chalcogen precursor does compriseSe. In some embodiments, a chalcogen precursor is selected fromprecursors comprising S, Se or Te. In some embodiments, a chalcogenprecursor comprises H₂S_(n), wherein n is from 4 to 10.

Suitable chalcogen precursors may include any number ofchalcogen-containing compounds so long as they include at least onechalcogen-hydrogen bond. In some embodiments the chalcogen precursor maycomprise a chalcogen plasma, chalcogen atoms or chalcogen radicals. Insome embodiments where an energized chalcogen precursor is desired, aplasma may be generated in the reaction chamber or upstream of thereaction chamber. In some embodiments the chalcogen precursor does notcomprise an energized chalcogen precursor, such as plasma, atoms orradicals. In some embodiments the chalcogen precursor may comprise achalcogen plasma, chalcogen atoms or chalcogen radicals formed from achalcogen precursor comprising a chalcogen-hydrogen bond, such as H₂S.In some embodiments a chalcogen precursor may comprise a chalcogenplasma, chalcogen atoms or chalcogen radicals such as a plasmacomprising sulfur, selenium or tellurium, preferably a plasma comprisingsulfur. In some embodiments, the plasma, atoms, or radicals comprisetellurium. In some embodiments, the plasma, atoms or radicals compriseselenium. In some embodiments the chalcogen precursor does not comprisea tellurium precursor.

In some embodiments, exposing the substrate to the chalcogen containingvapor phase reactant may comprise pulsing the chalcogen precursor (e.g.,hydrogen sulfide) over the substrate for a time period of between 0.1seconds and 2.0 seconds or from about 0.01 seconds to about 10 secondsor less than about 20 seconds, less than about 10 seconds or less thanabout 5 seconds. During the pulsing of the chalcogen precursor over thesubstrate the flow rate of the substituted chalcogen precursor may beless than 50 sccm, or less than 25 sccm, or less than 15 sccm, or evenless than 10 sccm.

The second vapor phase reactant comprising a chalcogen containingprecursor may react with the metal-containing molecules left on thesubstrate. In some embodiments, the second phase chalcogen precursor maycomprise hydrogen sulfide and the reaction may deposit a metal disulfideon the surface of the substrate.

Excess second source chemical and reaction byproducts, if any, may beremoved from the substrate surface, for example, by a purging gas pulseand/or vacuum generated by a pumping system. Purging gas is preferablyany inert gas, such as, without limitation, argon (Ar), nitrogen (N₂),or helium (He). A phase is generally considered to immediately followanother phase if a purge (i.e., purging gas pulse) or other reactantremoval step intervenes.

The deposition cycle in which the substrate is alternatively contactedwith the first vapor phase reactant (i.e., the metal containingprecursor) and the second vapor phase reactant (i.e., the chalcogencontaining precursor) may be repeated two or more times until a desiredthickness of a metal chalcogenide is deposited. It should be appreciatedthat in some embodiments of the disclosure, the order of the contactingof the substrate with the first phase reactant and the second vaporphase reactant may be such that the substrate is first contacted withthe second vapor phase reactant followed by the first vapor phasereactant. In addition, in some embodiments, the cyclical depositionprocess may comprise contacting the substrate with the first vapor phasereactant (i.e., the metal containing precursor) one or more times priorto contacting the substrate with the second vapor phase reactant (i.e.,the chalcogen containing precursor) one or more times and similarly mayalternatively comprise contacting the substrate with the second vaporphase reactant one or more times prior to contacting the substrate withthe first vapor phase reactant one or more times. In addition, someembodiments of the disclosure may comprise non-plasma reactants, e.g.,the first and second vapor phase reactants are substantially free ofionized reactive species. In some embodiments, the first and secondvapor phase reactants are substantially free of ionized reactivespecies, excited species or radical species. For example, both the firstvapor phase reactant and the second vapor phase reactant may comprisenon-plasma reactants to prevent ionization damage to the underlyingsubstrate and the associated defects thereby created.

The cyclical deposition processes described herein, utilizing a metalcontaining precursor and a chalcogen containing precursor to form ametal chalcogenide thin film, may be performed in an ALD or CVDdeposition system with a heated substrate. For example, in someembodiments, methods may comprise heating the substrate to temperatureof between approximately 80° C. and approximately 150° C., or evenheating the substrate to a temperature of between approximately 80° C.and approximately 120° C. Of course, the appropriate temperature windowfor any given cyclical deposition process, such as, for an ALD reaction,will depend upon the surface termination and reactant species involved.Here, the temperature varies depending on the precursors being used andis generally at or below about 700° C. In some embodiments, thedeposition temperature is generally at or above about 100° C. for vapordeposition processes, in some embodiments the deposition temperature isbetween about 100° C. and about 250° C., and in some embodiments thedeposition temperature is between about 120° C. and about 200° C. Insome embodiments the deposition temperature is below about 500° C.,below about 400° C. or below about 300° C. In some instances thedeposition temperature can be below about 200° C., below about 150° C.or below about 100° C., for example, if additional reactants or reducingagents are used in the process. In some instances the depositiontemperature can be above about 20° C., above about 50° C. and aboveabout 75° C. In some embodiments of the disclosure, the depositiontemperature i.e., the temperature of the substrate during deposition isapproximately 150° C.

In some embodiments the growth rate of the metal chalcogenide thin filmis from about 0.005 Å/cycle to about 5 Å/cycle, from about 0.01 Å/cycleto about 2.0 Å/cycle. In some embodiments the growth rate of the film ismore than about 0.05 Å/cycle, more than about 0.1 Å/cycle, more thanabout 0.15 Å/cycle, more than about 0.20 Å/cycle, more than about 0.25Å/cycle or more than about 0.3 Å/cycle. In some embodiments the growthrate of the film is less than about 2.0 Å/cycle, less than about 1.0Å/cycle, less than about 0.75 Å/cycle, less than about 0.5 Å/cycle orless than about 0.2 Å/cycle. In some embodiments of the disclosure, thegrowth rate of the metal chalcogenide is approximately 0.18 Å/cycle.

The embodiments of the disclosure may comprise a cyclical depositionwhich may be illustrated in more detail by method 100 of FIG. 1. Themethod 100 may begin with process block 110 which comprises providing asubstrate into a reaction chamber and heating the substrate to thedeposition temperature, for example, the substrate may comprise a bulksilicon substrate, the reaction chamber may comprise an atomic layerdeposition reaction chamber and the substrate may be heated to adeposition temperature of approximately 150° C. The method 100 maycontinue with process block 120 which comprises contacting the substratewith a metal containing vapor phase reactant, for example, the substratemay be contacted with tin (IV) acetate (Sn(OAc)₄) for a time period ofapproximately 1 second. Upon contacting the substrate with the metalcontaining precursor, the excess metal containing precursor and anybyproducts may be removed from the reaction chamber by a purge/pumpprocess. The method 100 may continue with process block 130 whichcomprises contacting the substrate with chalcogen containing vapor phasereactant, for example, the substrate may be contacted with hydrogensulfide (H₂S) for a time period of approximately 4 seconds. Uponcontacting the substrate with the chalcogen containing precursor, theexcess chalcogen containing precursor and any byproducts may be removedfrom the reaction chamber by purge/pump process.

The method wherein the substrate is alternately and sequentiallycontacted with the at least one metal containing vapor phase reactantand contacted with the at least one chalcogen containing vapor phasereactant may constitute one deposition cycle. In some embodiments of thedisclosure, the method of depositing a metal chalcogenide (e.g., a metaldichalcogenide) may comprise repeating the deposition cycle two or moretimes. For example, the method 100 may continue with decision gate 140which determines if the method 100 continues or exits. The decision gateof process block 140 is determined based on the thickness of the metalchalcogenide film deposited, for example, if the thickness of the metalchalcogenide film is insufficient for the desired device structure, thenthe method 100 may return to process block 120 and the processes ofcontacting the substrate with a metal containing vapor phase reactantand contacting the substrate with a chalcogen containing vapor phasereactant may be repeated two or more times. Once the metal chalcogenidefilm has been deposited to a desired thickness the method may exit 150and the metal chalcogenide film may be subjected to additional processesto form a device structure.

In some embodiments of the disclosure, the as-deposited metalchalcogenide thin film may be at least partially crystalline. Forexample, FIG. 2 illustrates grazing incidence x-ray diffraction (GIXRD)data for three (3) non-limiting examples of tin disulfide thin films,deposited utilizing the atomic layer deposition methods disclosedwithin, employing tin (IV) acetate (Sn(OAc)₄) as the tin containingprecursor and hydrogen sulfide (H₂S) as the chalcogen containingprecursor, at a deposition temperature of approximately 150° C. TheGIXRD data illustrated in FIG. 2 demonstrates tin disulfide thin filmsdeposited with different Sn(OAc)₄ pulse periods, for example, the datalabelled as 202 illustrates a tin disulfide thin film deposited with aSn(OAc)₄ pulse period of 0.2 second, the data labelled as 204illustrates a tin disulfide thin film deposited with a Sn(OAc)₄ pulseperiod of 1 second and the data labelled as 206 illustrates a tindisulfide thin film deposited with a Sn(OAc)₄ pulse period of 2 seconds.The peak in the GIXRD data for the three (3) tin disulfide thin filmcorresponds to the (001) crystallographic orientation. Therefore, insome embodiments of the disclosure, depositing a tin dichalcogenide thinfilm comprises depositing a tin disulfide with a predominant (001)crystallographic orientation.

FIG. 3 illustrates GIXRD data for three (3) non-limiting examples of tindisulfide thin films, deposited utilizing the atomic layer depositionmethods disclosed within, employing tin (IV) acetate (Sn(OAc)₄) as thetin containing precursor and hydrogen sulfide (H₂S) as the chalcogencontaining precursor, at a deposition temperature of approximately 150°C. The GIXRD data illustrated in FIG. 3 demonstrates tin disulfide thinfilms deposited with different H₂S pulse periods, for example, the datalabelled as 302 illustrates a tin disulfide film deposited with a H₂Spulse period of 8 seconds, the data labelled as 304 illustrates a tindisulfide film deposited with a H₂S pulse period of 4 seconds and thedata labelled as 306 illustrates a tin disulfide film deposited with aH₂S pulse period of 2 seconds. As demonstrated previously, the peak inthe GIXRD data for the three (3) tin disulfide thin films corresponds tothe (001) crystallographic orientation. In addition, the peak in theGIXRD increases in intensity with an increased H₂S pulse period,demonstrating that the crystallinity of the tin disulfide thin filmincreases with increased H₂S pulse time. Therefore, in some embodimentsof the disclosure, the deposition of a tin disulfide thin film comprisespulsing the chalcogen containing precursor (e.g., H₂S) for a time periodgreater than approximately 2 seconds, or greater than approximately 4seconds, or even greater than approximately 8 seconds.

Although the as-deposited metal chalcogenide thin films may be at leastpartially crystalline, the crystallization of the metal chalcogenidethin films may proceed slowly during the deposition process, such thatthinner films may be less crystalline than thicker films. This may beproblematic when the metal chalcogenide thin films comprise a 2Dmaterial with a thickness of less than approximately 10 nanometers.Therefore, in some embodiments of the disclosure, the as-deposited metalchalcogenide thin films may be subjected to a post-deposition annealingprocess to improve the crystallinity of the metal chalcogenide thinfilms. For example, in some embodiments, the method of depositing themetal chalcogenide may further comprise a post-deposition annealing ofthe metal chalcogenide at a temperature between approximately 150° C.and approximately 300° C. In some embodiments, annealing of the metalchalcogenide may comprise heating the metal chalcogenide to atemperature of approximately less than 800° C., or approximately lessthan 600° C., or approximately less than 500° C., or even approximatelyless than 400° C. In some embodiments, the post-deposition annealing ofthe metal chalcogenide thin film may be performed in an atmospherecomprising a chalcogen, for example, the post-deposition annealingprocess may be performed in an ambient comprising a chalcogenidecompound, for example sulfur compounds, such as, a hydrogen sulfide(H₂S) atmosphere. In some embodiments, the post-deposition annealing ofthe metal chalcogenide thin film may be performed for a time period ofless than 1 hour, or less than 30 minutes, or less than 15 minutes, oreven less than 5 minutes. In some embodiments, the post-depositionannealing of the metal chalcogenide thin film, such as a tindichalcogenide thin film, may be performed in an atmosphere notcomprising chalcogens, such as S, Se, or Te, for example, in inert gasambient such as N₂, or noble gas, such as Ar or He, or in hydrogencontaining ambient such as H₂ or H₂/N₂ ambient.

Thin films comprising a metal chalcogenide film, such as, for example,tin disulfide thin films, deposited according to some of the embodimentsdescribed herein may be continuous thin films comprising a 2D material.In some embodiments the thin films comprising a metal chalcogenide filmdeposited according to some of the embodiments described herein may becontinuous at a thickness below about 100 nm, below about 60 nm, belowabout 50 nm, below about 40 nm, below about 30 nm, below about 25 nm, orbelow about 20 nm or below about 15 nm or below about 10 nm or belowabout 5 nm or lower. The continuity referred to herein can be physicallycontinuity or electrical continuity. In some embodiments the thicknessat which a film may be physically continuous may not be the same as thethickness at which a film is electrically continuous, and the thicknessat which a film may be electrically continuous may not be the same asthe thickness at which a film is physically continuous.

FIG. 4 illustrates a cross sectional high-angle annular dark-fieldscanning transmission electron microscopy (HAADF-STEM) image ofstructure comprising a tin dichalcogenide 2D material depositedaccording to the embodiments of the disclosure. The HAADF-STEM imageillustrates a structure comprising a silicon substrate, silicon dioxide(SiO₂) disposed over the silicon substrate and a tin disulfide 2Dmaterial disposed over the silicon dioxide. The structure may furthercomprise a layer of carbon (C) disposed over the tin disulfide, whereinthe layer of carbon (C) is applied as part of the imaging procedure.FIG. 4 clearly demonstrates a crystalline tin disulfide (SnS₂) 2Dmaterial, with a 2D crystal structure, and a thickness of approximatelyless than 8 nanometers.

The tin dichalcogenide thin film deposited by the embodiments of thedisclosure may comprise tin disulfide and may take the form SnS_(x)wherein x may range from approximately 0.75 to approximately 2.8, orwherein x may range from approximately 0.8 to approximately 2.5, orwherein x may range from 0.9 to approximately 2.3, or alternativelywherein x may range from approximately 0.95 to approximately 2.2. Theelemental composition ranges for SnS_(x) may comprise Sn from about 30atomic % to about 60 atomic %, or from about 35 atomic % to about 55atomic %, or even from about 40 atomic % to about 50 atomic %.Alternatively the elemental composition ranges for SnS_(x) may compriseS from about 25 atomic % to about 75 atomic %, or S from about 30 atomic% to about 60 atomic %, or even S from about 35 atomic % to about 55atomic %.

In some embodiments of the disclosure, the phase of the metalchalcogenide, for example, tin disulfide, may be determined utilizingRaman spectroscopy. For example, FIG. 5 illustrates the Raman spectra,measured with a 325 nanometer laser, of a 7 nanometer thick tindisulfide thin film after annealing at a temperature of 250° C. TheRaman spectrum illustrated in FIG. 5 clearly shows a peak in intensityat 313 cm′ corresponding to the SnS₂ peak. No peaks from other SnSphases, such as SnS or Sn₂S₃, were detected in the measurement.Therefore, in some embodiments of the disclosure, depositing a tindichalcogenide comprises depositing a tin disulfide thin film with astoichiometry given by SnS₂.

In additional embodiments, the SnS may comprise less than about 20atomic % oxygen, less than about 10 atomic % oxygen, less than about 5atomic % oxygen, or even less than about 2 atomic % oxygen. In furtherembodiments, the SnS may comprise less than about 10 atomic % hydrogen,or less than about 5 atomic % of hydrogen, or less than about 2 atomic %of hydrogen, or even less than about 1 atomic % of hydrogen. In yetfurther embodiments, the SnS may comprise less than about 10 atomic %carbon, or less than about 5 atomic % carbon, or less than about 2atomic % carbon, or less than about 1 atomic % of carbon, or even lessthan about 0.5 atomic % carbon. In the embodiments outlined herein, theatomic concentration of an element may be determined utilizingRutherford backscattering (RBS).

In some embodiments of the disclosure, the metal chalcogenide thin filmmay be deposited on a three-dimensional structure. In some embodiments,the step coverage of the metal chalcogenide thin film may be equal to orgreater than about 50%, greater than about 80%, greater than about 90%,about 95%, about 98%, or about 99% or greater in structures havingaspect ratios (height/width) of more than about 2, more than about 5,more than about 10, more than about 25, more than about 50, or even morethan about 100.

In some embodiments a metal chalcogenide thin film, such as a tindichalcogenide thin film comprising, tin and a chalcogen depositedaccording to some of the embodiments described herein may be crystallineor polycrystalline. In some embodiments, a metal chalcogenide thin filmdeposited according to some of the embodiments described herein may havea thickness from about 20 nm to about 100 nm. In some embodiments, ametal chalcogenide thin film deposited according to some of theembodiments described herein may have a thickness from about 20 nm toabout 60 nm. In some embodiments, a metal chalcogenide thin filmdeposited according to some of the embodiments described herein may havea thickness greater than about 20, greater than about 30 nm, greaterthan about 40 nm, greater than about 50 nm, greater than about 60 nm,greater than about 100 nm, greater than about 250 nm, greater than about500 nm, or greater. In some embodiments a metal chalcogenide thin filmdeposited according to some of the embodiments described herein may havea thickness of less than about 50 nm, less than about 30 nm, less thanabout 20 nm, less than about 15 nm, less than about 10 nm, less thanabout 5 nm, less than about 3 nm, less than about 2 nm, or even lessthan about 1 nm.

In some embodiments a metal chalcogenide thin film, such as a tin orgermanium dichalcogenide thin film deposited according to some of theembodiments described herein may have a thickness of equal or less thanabout 10 monolayers of metal chalcogenide material, equal or less thanabout 7 monolayers of metal chalcogenide material, equal or less thanabout 5 monolayers of metal chalcogenide material, equal or less thanabout 4 monolayers of metal chalcogenide material, equal or less thanabout 3 monolayers of metal chalcogenide material, equal or less thanabout 2 monolayers of metal chalcogenide material, or even equal or lessthan about 1 monolayer of metal chalcogenide material.

The metal chalcogenide films deposited by the cyclical depositionprocesses disclosed herein may be utilized in a variety of contexts,such as in the formation of semiconductor device structures. One ofskill in the art will recognize that the processes described herein areapplicable to many contexts, including the fabrication of transistors.

As a non-limiting example, and with reference to FIG. 6, a semiconductordevice structure 600 may comprise a field effect transistor (FET) whichmay include a silicon substrate 602 and a silicon dioxide (SiO₂) layer604 disposed over the silicon substrate 602. The semiconductor devicestructure 600 may further comprise a source region 606 and a drainregion 608. Disposed between the source and drain regions is a thin filmof a metal chalcogenide 610 deposited according to the embodiments ofthe disclosure. The thin film of metal chalcogenide may comprise a thinlayer of tin disulfide and may consist of the channel region of the FETstructure. In some embodiments of the disclosure the thin layer of tindisulfide may have thickness of less than 10 nm, or less than 5 nm, oreven less than 1 nm. The semiconductor device structure 600 may furthercomprise a gate dielectric layer 612 disposed over the thin film of tindisulfide, wherein the gate dielectric layer 612 may comprise hafniumdioxide (HfO₂). The semiconductor device structure 600 may furthercomprise a gate electrode 614 disposed over the thin layer of tindisulfide 610.

Embodiments of the disclosure may also include a reaction systemconfigured for forming the metal chalcogenide films of the presentdisclosure. In more detail, FIG. 7 schematically illustrates a reactionsystem 700 including a reaction chamber 702 that further includesmechanism for retaining a substrate (not shown) under predeterminedpressure, temperature, and ambient conditions, and for selectivelyexposing the substrate to various gases. A precursor reactant source 704may be coupled by conduits or other appropriate means 704A to thereaction chamber 702, and may further couple to a manifold, valvecontrol system, mass flow control system, or mechanism to control agaseous precursor originating from the precursor reactant source 704. Aprecursor (not shown) supplied by the precursor reactant source 704, thereactant (not shown), may be liquid or solid under room temperature andstandard atmospheric pressure conditions. Such a precursor may bevaporized within a reactant source vacuum vessel, which may bemaintained at or above a vaporizing temperature within a precursorsource chamber. In such embodiments, the vaporized precursor may betransported with a carrier gas (e.g., an inactive or inert gas) and thenfed into the reaction chamber 702 through conduit 704A. In otherembodiments, the precursor may be a vapor under standard conditions. Insuch embodiments, the precursor does not need to be vaporized and maynot require a carrier gas. For example, in one embodiment the precursormay be stored in a gas cylinder. The reaction system 700 may alsoinclude additional precursor reactant sources, such precursor reactantsource 706 which may also be coupled to the reaction chamber by conduits706A as described above.

A purge gas source 708 may also be coupled to the reaction chamber 702via conduits 708A, and selectively supplies various inert or noble gasesto the reaction chamber 702 to assist with the removal of precursor gasor waste gasses from the reaction chamber. The various inert or noblegasses that may be supplied may originate from a solid, liquid or storedgaseous form.

The reaction system 700 of FIG. 7, may also optionally comprise annealstation 712, wherein the metal chalcogenide may be undergo a post-growthanneal process. In some embodiments, a post-growth anneal process may becarried out in the reaction chamber 702, whereas in some embodiments themetal chalcogenide thin film may be transferred (e.g., under acontrolled atmosphere) to an anneal station 712, wherein the post-growthannealing process may be performed under a desired gaseous environment.

The reaction system 700 of FIG. 7, may also comprise a system operationand control mechanism 710 that provides electronic circuitry andmechanical components to selectively operate valves, manifolds, pumpsand other equipment included in the reaction system 700. Such circuitryand components operate to introduce precursors, purge gasses from therespective precursor sources 704, 706 and purge gas source 708. Thesystem operation and control mechanism 710 also controls timing of gaspulse sequences, temperature of the substrate and reaction chamber, andpressure of the reaction chamber and various other operations necessaryto provide proper operation of the reaction system 700. The operationand control mechanism 710 can include control software and electricallyor pneumatically controlled valves to control flow of precursors,reactants and purge gasses into and out of the reaction chamber 702. Thecontrol system can include modules such as a software or hardwarecomponent, e.g., a FPGA or ASIC, which performs certain tasks. A modulecan advantageously be configured to reside on the addressable storagemedium of the control system and be configured to execute one or moreprocesses.

Those of skill in the relevant arts appreciate that other configurationsof the present reaction system are possible, including different numberand kind of precursor reactant sources and purge gas sources. Further,such persons will also appreciate that there are many arrangements ofvalves, conduits, precursor sources, purge gas sources that may be usedto accomplish the goal of selectively feeding gasses into reactionchamber 702. Further, as a schematic representation of a reactionsystem, many components have been omitted for simplicity ofillustration, and such components may include, for example, variousvalves, manifolds, purifiers, heaters, containers, vents, and/orbypasses.

The example embodiments of the disclosure described above do not limitthe scope of the invention, since these embodiments are merely examplesof the embodiments of the invention, which is defined by the appendedclaims and their legal equivalents. Any equivalent embodiments areintended to be within the scope of this invention. Indeed, variousmodifications of the disclosure, in addition to those shown anddescribed herein, such as alternative useful combination of the elementsdescribed, may become apparent to those skilled in the art from thedescription. Such modifications and embodiments are also intended tofall within the scope of the appended claims.

What is claimed is:
 1. A method for depositing a metal chalcogenide on asubstrate by cyclical deposition, the method comprising: contacting thesubstrate with at least one metal containing vapor phase reactantcomprising, a partial chemical structure represented by the formulaM-O—C, wherein “M” represents a metal atom, wherein “0” represents anoxygen atom, and wherein “C” represents a carbon atom, and wherein themetal atom is bonded to the oxygen atom, and wherein the oxygen atom isbonded to the carbon atom; and contacting the substrate with at leastone chalcogen containing vapor phase reactant.
 2. The method of claim 1,wherein the metal chalcogenide comprises a metal dichalcogenide.
 3. Themethod of claim 1, wherein the at least one chalcogen containing vaporphase reactant comprises S, Se, or Te.
 4. The method of claim 1, whereinthe metal chalcogenide comprises an oxygen (O) content less than 10atomic-%.
 5. The method of claim 1, wherein the cyclical depositioncomprises atomic layer deposition.
 6. The method of claim 1, wherein thecyclical deposition comprises cyclical chemical vapor deposition.
 7. Themethod of claim 1, wherein the metal containing vapor phase reactantcomprises at least one of a tin (Sn) containing vapor phase reactant, ora germanium (Ge) containing vapor phase reactant.
 8. The method of claim7, wherein the at least one tin (Sn) containing vapor phase reactant isrepresented by the chemical formula Sn(OR)_(x), wherein R is a C₁-C₅alkyl group and x is an integer from 2-6.
 9. The method of claim 7,wherein the at least one tin (Sn) containing vapor phase reactantcomprises tin (IV) acetate.
 10. The method of claim 7, wherein the atleast one tin (Sn) containing vapor phase reactant is represented by thepartial formula:

wherein a tin (Sn) atom is bonded to two oxygen (O) atoms, and saidoxygen (O) atoms are bonded to a carbon atom (C) through one single bondand one double bond, and R comprises a hydrocarbon group.
 11. The methodof claim 7, wherein the at least one tin (Sn) containing vapor phasereactant is represented by the partial formula:

wherein a tin (Sn) atom is bonded to two oxygen (O) atoms, and saidoxygen (O) atoms are bonded to a carbon atom (C) through one single bondand one double bond, and R is a hydrocarbon group, and L is a furtherhydrocarbon group.
 12. The method of claim 7, wherein the at least onetin (Sn) containing vapor phase reactant is represented by the partialchemical formula:L-Sn—O—C wherein a tin (Sn) atom is bonded to an oxygen (O) atom, andsaid oxygen (O) atom is bonded to a carbon atom (C), and L is ahydrocarbon group.
 13. The method of claim 1, wherein the at least onechalcogen containing vapor phase reactant comprises hydrogen sulfide(H₂S), hydrogen selenide (H₂Se), dimethyl sulfide ((CH₃)₂S), or dimethyltelluride (CH₃)₂Te.
 14. The method of claim 1, wherein the methodcomprises at least one deposition cycle in which the substrate isalternately and sequentially contacted with the at least metalcontaining vapor phase reactant and the at least one chalcogencontaining vapor phase reactant.
 15. The method of claim 14, wherein thedeposition cycle is repeated two or more times.
 16. The method of claim1, further comprising heating the substrate to a temperature ofapproximately greater than 150° C.
 17. The method of claim 16, furthercomprising heating the substrate to a temperature of less thanapproximately 500° C.
 18. The method of claim 1, wherein the metalchalcogenide comprises tin disulfide.
 19. The method of claim 1, whereinthe metal chalcogenide comprises germanium disulfide.
 20. The method ofclaim 1, further comprising a post-deposition annealing of the metalchalcogenide at a temperature between approximately 150° C. andapproximately 300° C.
 21. The method of claim 20, wherein thepost-deposition annealing of the metal chalcogenide is performed in ahydrogen sulfide (H₂S) atmosphere.
 22. A semiconductor device structurecomprising a metal chalcogenide deposited by the method of claim
 1. 23.The semiconductor device structure of claim 24, wherein the metalchalcogenide comprises at least a portion of the channel region in atransistor structure.
 24. A reaction system configured to perform themethod of claim 1.